I got 22 klx 300r over a month ago and ran fine until one day I dumped it and rode pretty good on it. it felt hot on my leg and looked down the header pipe was lit right up cherry red. Ever since then I can ride it for like 5 minutes and then it’s cherry red hot already! I could ride it for hours before. Anyway I changed the oil I flushed and change the coolant. Checked the water pump it spun when I started it, the radiator was cycling so that’s good. So not sure what else it could be? Google said something about efi issues I don’t know.

 

While riding or sitting still for any length of time?

 

Sounds like unwanted air is being introduced into the engine someplace making it run lean and hot.

When you dumped the bike, what parts of the bike got hit? Check to see if any air hoses got pulled off.

DO NOT ride the bike until you find the cause.

Another more unlikely possibility is something got knocked loose inside the muffler blocking the exhaust flow. So if you have a removeable end cap you could take it off and have a look. If you can't, remove the slip on muffler and shake it to see if you can hear anything rattling inside. Also check the connection between the head pipe and the engine to see if it is sealed properly and not introducing unwanted air into the exhaust.

A pinched fuel line could make the engine run lean and overheat the exhaust.

Does the head pipe get red hot if you start the engine and just let it idle without touching the throttle? If you have a PAIR valve. Block its air hose and see if the engine still runs hot. Possibly the pair valve is open all the time introducing too much air into the headpipe causing unburned hydrocarbons to burn hotter inside it.

Those are all the possibilities I can think of. Unwanted air is the likely culprit. Let us know what you find.

DO NOT ride the bike until you find the cause.

 

I would be amazed if falling off caused anything to happen. After all, these are essentially dirt bikes with flexible plastics to take a crash without serious damage. You may want to see that your oxygen sensor is still hooked up. From there if you are really concerned I take it you have a new enough bike that the warranty is in effect and a dealership service department could tell you if you have an actual problem..

Most single wall exhausts will heat up to glowing temps if left sitting and idling. The exhaust gasses will easily run between 1000-1400° F and steel will start to glow at around 800-900°F. So, no it isn't unusual if the bike is sitting still. The air flow over the exhaust will cool the exhaust below glowing temps. I know this from both reading on the topic and from personal experience.

Here is Ryan Villipoto's Kawasaki with the head pipe glowing on the start line at a race. I'm guessing they have the jetting and all pretty much spot on.



So consider are you letting it sit and idle too long? It doesn't take long for an exhaust to start to glow, a few minutes. It will start to appear sooner at night. If you ride the bike you will find the glow gone in a matter of a couple seconds.

 

I just purchased a 2021 KXL300R has the same problem as Buckskii. Bike has maybe 50 hours on it. exhaust gets cherry red within a couple of minutes riding.
Any help would be appreciated.